JPS60177005A - Information recording material of optical type - Google Patents

Abstract

PURPOSE:An information recording material of optical type usable for optical disc of great capacity type, having improved transparency, molding properties, water-vapor resistance, and heat resistance, comprising a polyvinyl acetal acetalized with a specific aldehyde, having high acetalization degree, as a base material. CONSTITUTION:A resin composition containing a polyvinyl acetal having >=65% acetalization degree, wherein >=5mol% polyvinyl acetal is acetalized with one or more aldehydes selected from an aliphatic cyclic aldehyde (e.g., cyclohexylaldehyde, alpha-camphorenealdehyde, 4-methylcyclohexenealdehyde, etc.), an aromatic aldehyde (e.g., benzaldehyde, phenylpropylaldehyde, etc.), and a hetrocyclic aldehyde (e.g., furfural, etc.) is used as the desired recording material.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an optical information recording medium for recording and reproducing signals by reflecting or transmitting laser light.

(Prior Art) Video discs, audio discs, information file discs for combiators, etc. have traditionally been made of highly transparent polymethyl methacrylate or polycarbonate. Polymethyl methacrylate has excellent moldability and strength, but poor moisture resistance. Therefore, under high temperature and high humidity conditions, the molded product may warp, or crack as it repeatedly absorbs moisture and dries. Furthermore, impact resistance decreases. JP-A-58-5354 and JP-A-58-13652 disclose resins with improved moisture resistance by copolymerizing several types of polymethacrylates. However, as long as polymethacrylate is used as the main ingredient, moisture resistance is still insufficient.

On the other hand, polycarbonate has a low surface hardness and is easily scratched. Moreover, the moldability is poor and the orientation during molding remains in the resin, resulting in large birefringence. For this reason.

It cannot be used for large-capacity image type discs, large-capacity computer discs, etc. All other highly transparent resins have large birefringence and are therefore unsuitable for use in these disks. An example of a resin with excellent transparency and moisture resistance and low birefringence is polyvinyl acecool, which is mainly composed of polyvinyl butyral. If the heat resistance of polyvinyl acecool, which has such excellent properties, can be improved, an even more excellent information recording medium can be obtained.

(Object of the Invention) An object of the present invention is that it can be used in a large-capacity recording type optical disc. The object of the present invention is to provide an optical information recording medium that has excellent transparency, no birefringence, and excellent moldability, moisture resistance, and heat resistance.

(Structure of the Invention) The present invention provides a resin with excellent moisture resistance by increasing the degree of acetalization of highly transparent polyvinyl acecool, and which improves heat resistance by selecting the type of aldehyde used for acetalization. This was completed based on the inventor's knowledge that a resin with excellent properties could be obtained. Therefore, (1) the optical information recording medium of the present invention contains polyvinyl acecool having a degree of acetalization of 65 mol% or more, and a small amount of the polyvinyl acecool (both 5 mol% is aliphatic cyclic aldehyde and aromatic aldehyde). , and an aldehyde having a heterocycle, thereby achieving the above object.

This polyvinyl acetal is obtained by acetalizing polyvinyl alcohol by reacting an aldehyde under an acidic catalyst. If the degree of acetalization is low, hygroscopicity will be high due to residual hydroxyl groups.

The resin composition forming the recording medium of the present invention has an acetalization degree of 65 mol% or more, preferably 70 mol% or more, and therefore has excellent moisture resistance. In order to obtain such polyvinyl acecool, it is preferable that the raw material polyvinyl alcohol has high purity.

Therefore, when polyvinyl alcohol is obtained by saponifying polyvinyl acetate with an alkali.

It is preferable that the saponification degree is 95 mol% or more, in other words, the residual acetyl group is 5 mol% or less. If the residual degree of acetyl groups is high, the transparency of the recording medium will decrease.

When preparing polyvinyl acetal, in addition to the aliphatic aldehyde, one or more of aliphatic cyclic aldehydes, aromatic aldehydes, and aldehydes having a heterocycle are further used in order to impart heat resistance to the resin.

Aliphatic aldehydes include formaldehyde, acetaldehyde, and propylaldehyde.

Examples include n-butyraldehyde, dibutyraldehyde, decylaldehyde, dodecylaldehyde, and benzaldehyde. These aldehydes may be used alone or in combination.

Examples of aliphatic cyclic aldehydes include cyclohexylaldehyde, trimethylcyclohexylaldehyde, and dimethylcyclohexylaldehyde.

Methylcyclohexylaldehyde, cyclopentylaldehyde, methylcyclopentylaldehyde.

Saturated aldehydes such as decahydro-β-naphthaldehyde and cyclohexylacetaldehyde, α-camphorenaldehyde, and feranodral.

Examples include terpene aldehydes such as cyclocitral, trimethyltetrahydrobenzaldehyde, α-pyronenaldehyde, myrtenal, dihydromiltenal, camphenylan aldehyde, and 4-methylcyclohexenaldehyde and 3-methylcyclohexenaldehyde.

Examples of aromatic aldehydes include benzaldehyde, phenylacetaldehyde, phenylpropylaldehyde, tolualdehyde, dimethylbenzaldehyde, cuminaldehyde, and naphthylaldehyde.

Examples of aldehydes having a heterocycle include aldehydes having a furan ring such as furfural and 5-methylfurfural.

The above-mentioned aliphatic cyclic aldehydes, aromatic aldehydes, and aldehydes having a heterocycle may be used alone or in combination.

However, it is necessary that the total amount exceeds 5 mol% of the total aldehyde. If it is less than 5 mol%, sufficient heat resistance cannot be obtained. The aldehydes used may consist solely of these aldehydes.

゛ Polyvinyl acetal can be prepared by a commonly used method such as a dissolution method, a homogeneous method, and a precipitation method.

Alternatively, it may be prepared by saponifying polyvinyl acetate and subsequently acetalizing it.

The polyvinyl acetal resin thus prepared is molded by a commonly used method such as injection molding or press molding.

If necessary, commonly used additives such as anti-aging agents, antioxidants, and lubricants may be added.

(Example) The present invention will be described below with reference to Examples.

Large group and above (A) Preparation of polyvinyl acetal: Saponification degree 99.2
Polyvinyl alcohol 1 mol % and degree of polymerization 1500
00g was dissolved in 880g of distilled water. After adding 57 g of concentrated hydrochloric acid to this, 28.8 g of isobutyraldehyde was added dropwise over 15 minutes while maintaining the temperature at 14.4°C.

Ten minutes after the dropwise addition, a polyvinyl butyral precipitate was deposited. Further, 63.5 gt of cyclohexylaldehyde F was added, and the reaction system was heated and kept at 40°C for 10 hours.

This was cooled down and neutralized with baking soda. The obtained polyvinyl acetal was washed with water and dried at 70°C for 48 hours.

(B) Molding and performance evaluation of polyvinyl acecool =
The resin obtained in section (A) was injection molded under conditions of a cylinder temperature of 255°C and a mold temperature of 75°C. Obtained 1
, 2a+n x 120mm x 120mj injection molded plate after water absorption, water absorption rate, total light transmittance, haze value.

and birefringence were measured. The results are shown in the table below. Each measurement method is as shown below.

+11 Warpage after water absorption 2 Aluminum was vapor deposited on one side of the substrate of the above-mentioned molded plate, and a protective coating was further applied thereto to block water from entering from the vapor deposition surface. This sample was immersed in water at 20°C, and warpage at the center of the sample was measured after 72 hours.

(2) Water absorption rate: A molded plate that had not been subjected to vapor deposition treatment was immersed in water at 20°C, and the weight of the sample was measured after 72 hours, and the rate of increase was calculated.

(3) Total light transmittance: Measured by the method of ASTM D-1003.

(4) Haze value: Measured by the method of ASTM D-1003.

(5) Presence or absence of birefringence: The presence or absence of birefringence was investigated by sandwiching an undeposited molded plate between two polarizing plates, transmitting visible light, and observing interference fringes.

(6) Heat deformation temperature: ASTM D-648 (18,6
kg/CIA) method.

1 (A) Preparation of polyvinyl acecool: degree of saponification 99.2
Mol% 1 polyvinyl alcohol with degree of polymerization 1500 100
g to 100 g of distilled water and 70 g of isopropyl alcohol.
It was dispersed in 0 g of the mixed solution. After adding 57 g of concentrated hydrochloric acid to this, while stirring and keeping the temperature at 65°C, 2 g of isobutyraldehyde was added.
8.8 g and 95.8 g of 2,2,6-drimethylcyclohexylaldehyde were added. The temperature was maintained at 65° C. for 15 hours, and after neutralization, a large amount of water was added to precipitate. The obtained polyvinyl acecool resin was washed with water and heated at 70°C for 4
It was dried for 8 hours.

(B) Polyvinyl acecool-molding and performance evaluation: Same as Example 1.

Example 1 (A) Preparation of polyvinyl acecool The same procedure as in Example 1 was repeated except that 86.2 g of pheanodral was added instead of dichlorohexyl aldehyde.

(B) Molding and performance evaluation of polyvinyl acecool: Same as Example 1.

Inuse soil (A) Preparation of polyvinyl acecool: Example 1 except that the amount of isobutyraldehyde used was 61.3 g and the amount of cyclohexyl aldehyde was 12.7 g.
It is similar to

(B) Molding and performance evaluation of polyvinyl acecool: Same as Example 1.

Example 5 (A) Preparation of polyvinyl acecool Same as Example 1 except that 54.4 g of henzaldehyde was used instead of dichlorohexylaldehyde.

(B) Molding and performance evaluation of polyvinyl acecool: Same as Example 1.

(A) Preparation of polyvinyl acetal: Same as Example 1 except that 61.3 g of isobutyl aldehyde was used and 21.8 g of furfural was used instead of cyclohexyl aldehyde.

(B) Molding and performance evaluation of polyvinyl acecool: Same as Example 1.

Northern Flaming (A) Preparation of polyvinyl acecool: Same as Example 1 except that the amount of isobutyraldehyde used was 57.3 g and cyclohexylaldehyde was not used.

(B) Molding and performance evaluation of polyvinyl acecool: Same as Example 1.

It is molded using polymethyl methacrylate (F1000 manufactured by Wa Gas Kagaku Co., Ltd.) which is generally used as a resin for optical discs.

Performance evaluation was performed in the same manner as in Example 1.

(Effects of the Invention) As described above, the optical information recording medium of the present invention has excellent moisture resistance because it uses polyvinyl acecool having a high degree of acetalization as a base material. Since an aliphatic cyclic aldehyde, an aromatic aldehyde, or an aldehyde having a heterocycle is used for acetalization, the base material also has excellent heat resistance. Therefore, no warping or distortion occurs during storage. Since the molding of the base resin is excellent, the fine focus of the stamper can be transferred. No distortion or orientation remains during molding. This prevents information from being erroneously recorded or read. Therefore, if the recording medium of the present invention is used, it can be applied to many fields such as large-capacity image type disks and large-capacity computer disks.

Applicant Sekisui Chemical Co., Ltd. TeUtosho iiE7・X' (Voluntary) May 17, 1985 1. Indication of the case 1988 Patent Application No. 31786 2. Name of the invention Optical information recording Body 3. Relationship with the person making the amendment Patent applicant postal code 530 Address Patent Department 2-4-4 Nishitenma, Kita-ku, Osaka
(06) 365-2181 Patent Department Tokyo stationed Tl (
03) 434-9552 East Subject of amendment 01 Detailed explanation of the invention in the specification column 5, Contents of amendment (blind) In the 7th line of page 5 of the specification, "leptylaldehyde" was replaced with "inbutyl" Aldehyde” is corrected.

(2) On page 5 of the specification, from line 11 to line 7 from the bottom, [cyclohexylaldehyde, . aldehyde, methylcyclohexane aldehyde,” and amend it.

(3) Specification @ page 5, row 6 from the bottom.

“Methylcyclopentylaldehyde,” the male said. and correct it.

(4) "Cyclohexyl acetaldehyde" is replaced with "cyclohexane acetaldehyde" from line 5 to line 9 from the bottom of page 5, line 7 from the bottom of page 10 to line 4 from the bottom of the specification. In line 6, lines 1 to 2 of page 11, and lines 8 to 9 of page 11, the words ``cyclohexylaldehyde'' will be corrected to ``cyclohexanaldehyde.''

(6) 1" from the 8th line from the bottom of the specification to the 7th line from the bottom of the specification.
2,2,6-trimethylcyclohexylaldehyde," is replaced with "2@2,6-trimethylcyclohexanaldehyde,"
” he corrected.

(7) Page 12 of the specification is amended as shown in the attached sheet.

6. Attached tilting inventory 111 One or more documents containing the 12th page after amendment

Claims (1)

[Scope of Claims] 1. Contains polyvinyl acecool having a degree of acetalization of 65 mol% or more, and at least 5 mol% of the polyvinyl acecool is an aliphatic cyclic aldehyde. An optical recording medium comprising a resin composition acecooled with at least one selected from the group consisting of aromatic aldehydes and aldehydes having a heterocycle. 2. The recording medium according to claim 1, wherein the heterocycle is a furan ring.